These maps show what could happen next in Yemen — and how it could impact global politics

As Saudi Arabia and its coalition of partner Sunni states intervenes in the growing war within Yemen, the south Arabian country is taking on major geopolitical significance.

The conflict in Yemen is the the largest and most dangerous escalation in an ongoing series of proxy-battles between Sunni Saudi Arabia and Shiite Iran. Unlike other conflicts between the two regional powers in Syria and Iraq, however, Yemen is directly in Saudi Arabia's backyard. Increased instability there could threaten the Saudi Kingdom, which is why Riyad has directly intervened in the conflict.

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Saudi Arabia has convened a significant coalition of Sunni states in support of Yemen's government against the Iranian-supported Shiite Houthi rebels. Yemen's President Abd-Rabbu Mansour Hadi fled from the southern port city of Aden by boat on March 25 as Houthi forces moved on the city.

The Saudi-led coalition has so far only carried out aerial strikes against the Houthis. However, both Egypt and Saudi Arabia said that they were planning a possible ground offensive against the rebels.

Here's who's participating in the Saudi coalition, in a mission called Operation Decisive Storm:

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Currently, Houthi forces control most of western Yemen including the capital, Sanaa. Houthi forces have allied themselves with army units loyal to former Yemeni President President Ali Abdullah Saleh, who was forced to step down from power in 2011 during the Arab Spring.

These Houthi-led forces are battling against army units loyal to Hadi in the south, as well as against al Qaeda and Sunni tribes in central Yemen. Al Qaeda has proven to be among the most capable of the anti-Houthi forces. "Unfortunately the vanguard of Sunnis in Yemen has been Al Qaeda in the Arabian Peninsula, which is a very bad development for the US and the broader region," Oren Adaki, a research analyst at the Foundation for Defense of Democracies, told Business Insider.

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The current battle lines in Yemen largely reflect the country's sectarian makeup — although Yemen didn't have much history of sectarian conflict until recent years. The Houthis draw most of their power from the provincial city of Saadah, as well as the regions around Sanaa. The Houthis follow a form of Shia Islam called Zaydism, which is different from the revolutionary Shia Islam promulgated by the regime in Iran and is actually largely similar to the Sunni Islam practiced elsewhere in Yemen.

Map showing ethno-religious areas in Yemen. Reuters Prior to 1962, the Zaydi portions of Yemen were ruled under the Shia Mutawakkilite Kingdom of Yemen. However, the kingdom was overthrown by a pan-Arabist coup inspired by Egypt in 1962 leading to the North Yemen Civil War.

During the war, Saudi Arabia and Israel funneled support towards the Zaydi Shiites in an effort to weaken the Egyptian forces fighting in support of the Yemeni "Republicans" against the Zaydi "Royalists." Ultimately, the Republicans won.

After the North Yemen Civil War, Yemen was a divided country, with the Yemen Arab Republic in the north and the People's Democractic Republic of Yemen in the south. Their capitals were Sanaa and Aden, respectively.

After the fall of most of the world's Soviet-allied socialist regimes, the two countries merged together to form the Republic of Yemen in 1990 under President Saleh. Despite Yemen's unification, the country again seems to be sliding towards at least de-facto separation. The areas the Houthis now control are approximately in line with the borders of both the Yemen Arab Republic and the Mutawakkilite Kingdom before it.

"I don't even think it's accurate to think of Yemen as a single country anymore," Yemen specialist Gregory D. Johnson told The New York Times.

Regardless of how far the Houthis push their advance, the instability in Yemen could directly effect oil prices. Approximately 3.8 million barrels of oil and refined petroleum products pass through the Bab el-Mandeb waterway at Yemen's southern tip. This passage is only 18 miles wide at its narrowest point.

Instability in this passage, or even a closure of the waterways, would have a drastic impact upon global oil prices. Although the Bab el-Mandeb has not been threatened, the oil market is already on edge as the possibility emerges.